56 dodge with 315 engine what newer v8 will bolt right up to my 56 dodge car with powerflite trans?

I AM THINKING OF DOING AN EASY ENGINE SWAP TO REPLACE MY ORIGINAL 56 DODGE 315 V8 WITH A NEWER V8 THATS EASIER TO GET PERFORMANCE PARTS FOR .I WOULDN'T MIND RETAINING MY GOOD 56 POWERFLITE TRANS AS PART OF THE SWAP. WHAT PROBLEMS MIGHT I ENCOUNTER?